Carburetor for internalcombustion engines



Jan. 8, 1946. M. MALLORY 2,392,581

I CARBURETOR FOR INTERNAL-COMBUSTION ENGINES Filed June 25, 1945.

v INVENTOR. Nana/7 Mafia/y Patented Jan. 8, 1946 UNITED STATES PATENTOFFICE CARBURETOR FOR INTERNAL- COMBUSTION ENGINES Marion Mallory,Detroit, Mich.

Application June 23, 1945, Serial No. 601,200

Claims.

This invention relates to a carburetor for an internal combustionengine.

In the conventional carburetor an idle jet is provided on the engineside of the throttle valve which supplies all the fuel when the engineis idlingbecause there is not enough air flowing by the main jet in theventuri to draw fuel therefrom. When the throttle is moved toward openposition the velocity of the air flowing by themain jet in the venturiincreases and draws fuel from the main jet but the idle jet continues toflow fuel until the throttle has moved toward open position aconsiderable distance. The fuel feeding from the idle jet as thethrottle opens adds to the fuel feeding out of the main jet in thepartly opened throttle range to make a mixture of proper proportions forthe engine. When a sandwich governor is positioned between thecarburetor and the engine, under certain conditions the feeding of fuelfrom the idle jetis upset and the mixture becomes too lean. For example,if the main car-' buretor throttleis' held wide open and the governorvalve closes, there will be little or no suction around the idle jet andthe only fuel fed to the engine will come from the main jet. Further,since the air velocity by th main jet will be low, insuficient fuel willbe drawn from the main jet and the mixture will become too lean.

It is an object of this invention to produce a carburetor which can beused with an engine speed governor and which will remedy the abovepointed out defects and at all times supply correct fuel mixtures to theengine as required by operating conditions.

This object is obtained by the provision of an idle bypass fuel jetbetween the governor valve and the engine through which. fuel issupplied to the engine when the governor is almost closed.

The drawing i a vertical section showing my carburetor.

The parts of my carburetor are as follows: carburetor housing 4,governor body 2, intake passageway 3 having air inlet 6 and fuel mixtureoutlet 5 to the engine, float bowl b, fuel level Tl, venturi 8, main jet9, manually controlled throttle iii preferably of the butterfly type,idle jet l l, fuel passageway 52 between the idle jet and the floatbowl, automatically controlled governor valve i3, idle bypass jet it onthe engine side of governor valve l3, check valve l5, compressionspringi6 tending to hold valve l5 against seat ll.

It is understood that governor valve 83 is automatically operated andmay be any of the known automatically operated types of governor such asthe unbalanced velocity type governor valve, the

engine driven centrifugal weight actuated type of governor, or theintake passageway pressure actuated governor such as shown in mycopending application Serial No. 466,961, filed November 25, 1942.

The operation of my carburetor is as follows: Assuming that the engineis running at low speed and being controlled by the main carburetorthrottle Hi, there will be a sufilcient vacuum or suction at idleorifice II which will draw fuel through channel I! out of bowl 6. Whencontrolling the engine with the carburetor throttle It at idle or partlyopen throttle condition; the suction at orifice l i will be as high asit is at orifice l4 and therefore ball check I5 will be held closedagainst seat H by spring I6 because the vacuum or pressure above andbeneath the valve will be substantially equal. If throttle valve to isnow held wide open, as indicated in the dotted lines, and the governorstarts to check the engine speed and closes to a position, for example,as shown in the dotted lines, then orifice II will be near, or atsubstantially atmospheric pressure, and orifice It will be in the vacuumor sub-atmospheric pressure obtaining in the intake passageway on theengine side of governor valve It. The vacuum at orifice It will now drawcheck valve to downwardly off seat I! and fuel will now be drawn throughpassageway l 2 and out of bypas idle jet it which will be added to thelean mixture coming out of the main jet 9 to give the properlyproportioned fuel mixture under such operating conditions. Check valvel5 will remain closed on seat ill at all times except when thecarburetor throttle valve is opened far enough and overnor valve [33 isclosed far enough whereby orifice H is in a higher pressure than thepressure obtaining at orifice it. will be in a high pressure area andorifice id in a low pressure area.

I claim:

1. In a carburetor for an internal combustion engine having an intakepassageway, two throttle valves mounted in series in the intakepassageway, an idle jet in the intake passageway between said valves, asecond idle jet in the intake passageway on the engine side of saidvalves, a source of fuel connected to said jets, and means acutated bychanges of pressure in the intake passageway for controllingcommunication between said idle bypass jet and said source of fuel, saidpressure actuated means responding to open communication between thebypass fuel jet and its source of fuel when the pressure obtaining inthe intake passageway at said bypass jet is lower In other words,whereby. orifice ll 2 asoaeer than the pressure obtaining at the idlejet whereby fuel is drawn from the bypass jet into the intakepassageway.

2. In a carburetor for an internal combustion engine having an intakepassageway, first and second independently operatable throttle valves insaid intake passageway, said second throttle valve being positioned onthe engine side of thc and bypass jet such as occurs when the firstthrottle is substantially wide open and the second valve is partlyclosed so that the intake passageway pressure at the idle jet issubstantially atmospheric and a vacuum obtains in the intake passagewayat the-bypass jet whereby fuel is drawn into the intake passagewaythrough the bypass idle jet. 3. In a carburetor for aninternalcombustion engine having an intake passageway, first and secondindependently operatable throttle" valves in said intake passagewa saidsecond throttle valve being positioned on-the engine side of the tthrottle valve, an idle jet in the intake pass eway between saidthrottle valves, an idle bypass jet on the engine side of said secondthrottle valve, a source of fuel, a passageway connecting said idle jetswith each other and with said source of fuel, a check valve in saidpassageway between the idle Jet and the bypass jet arranged to open inresponse to intake passageway sudtion on the engine side of said secondvalve when the pressure obtaining in the intake passageway at saidbypass jet is lower than the pressure obtaining at the idle jet wherebyfuel is drawn from the bypass jet into the intake passageway. andresillent means tending to hold said check valve closed.

4. In a carburetor for an internal combustion engine having an intakepassageway, two throttle valves mounted in series in the intakepassageway, an idle jet in the intake passageway between said valves. asecond idle jet in the intake passageway on the engine side of saidvalves, a source of fuel connected to said jets, and means a tuated bychanges of pressure in the intake passageway for controllingcommunication between said idle bypass jet and said source of fuel, aventuri in said intake passageway on the atmosphere side of saidthrottle valves, a main jet positioned in said venturi, a source of fuelconnected to said main jet whereby the flow of air through said venturitends to draw fuel from said main jet at a rate of flow increasing withthe velocity of the air flowing through said venturi, said pressureactuated means responding to open communication between the bypass fueljet and its source of fuel when the pressure obtaining in the intakepassageway at said'bypass jet is lower than the pressure obtaining atthe idle jet whereby fuel is drawn from 'the bypass jet into the intakepassageway.

- 5. In a carburetor for an internal combustion engine having an intakepassageway, a'venturi in said intake passageway, first and secondindependently operatable throttle valves in said intake passageway onthe engine side of said venturi, said second throttle valve beingpositioned on the engine side of the first throttle valve, 9. main jetin said venturi, an idle jet in the intake passageway between saidthrottle valves, an idle bypass jet on the engine side of said secondthrottle valve, 9. source of fuel, a passageway connecting said idlejets with each other and with said source of fuel, a passagewayconnecting said main jet with said source of fuel, pressure actuatedvalve means in said passageway between the idle jet and the bypass jetopening in response to a difference in pressure in the intake passa ewayat the idle jet and bypass jet such as occurs when 40 the first throttleis substantially wide open and the second valve-is partly closed so thatthemtake passageway pressure at the idle jet is substantiallyatmospheric and a vacuum obtains in the intake passageway at the bypassjet whereby fuel is drawn into the intake passageway through the bypassidle jet and commingles with fuel drawn from the main jet.

MARION MALLORY.

